Unaspirated Plosives Research Articles

Ghebi Stops: Inventory, Distribution and Voice Onset Time (VOT)

This study focuses on the Ghebi dialect spoken in Pakistan's northwest. The study primarily examines stops of the Ghebi dialect at word initial, medial, and final positions while also investigating the Voice Onset Time (VOT) values of Ghebi stops. Through the analysis of minimal pairs, 16 plosive sounds have been discerned in Ghebi, characterized by a four-way voicing contrast and articulated at four distinct locations. The voiceless unaspirated plosives consist of /p, t̪, ʈ, k/, while the voiceless aspirated plosives include /ph, t̪ʰ, ʈʰ, kʰ/. Voiced unaspirated plosives are represented by /b, d̪, ɖ, g/, whereas voiced aspirated plosives feature /bʰ, d̪ʰ, ɖʰ, gʰ/. VOT values were quantified using PRAAT, with voiceless stops exhibiting shorter VOT values. It was found that /ʈ/ has the shortest VOT value, while /ɖ/ has the longest VOT value. This present study will greatly contribute to the documentation and exploration of the Ghebi dialect.

Production and Perception of Mandarin Laryngeal Contrast: The Role of Post-plosive F0

This study examines the relation between plosive aspiration and post-plosive f0 (fundamental frequency) in the production and perception of the laryngeal contrast in Mandarin. Production data from 25 Mandarin speakers showed that, in word onsets, VOTs (voice onset time) of aspirated and unaspirated plosives were different, as expected. At the same time, the speakers produced different post-plosive f0 between aspirated and unaspirated plosives, but the difference varied according to the lexical tones – post-aspirated f0 was higher than post-unaspirated f0 in high-initial tones (i.e., lexical tones with high onset f0), but the pattern was the opposite and less robust in low-initial tones. In the perception of the same participants, VOT was the primary cue to aspiration but, when VOT was ambiguous, high post-plosive f0 yielded more aspirated responses in general. We claim that the asymmetry in f0 perturbation between high-initial and low-initial tones in production arises from different laryngeal maneuvers for different tonal targets. In low-initial tones, in which the vocal folds are slack and the glottal opening is wider, aspirated plosives have a lower subglottal air pressure than unaspirated plosives at the voicing onset, resulting in lower post-aspirated f0 than post-unaspirated f0. But in high-initial tones, the vocal folds are tense, which requires a higher trans-glottal pressure threshold to initiate phonation at the onset of voicing. As a result, the subglottal pressure does not decrease as much. Instead, the faster airflow in aspirated than unaspirated plosives gives rise to the pattern that post-aspirated f0 is higher than post-unaspirated f0. Regardless of this variation in production, our perception data suggest that Mandarin listeners generalize the f0 perturbation patterns from high-initial tones and associate high post-plosive f0 with aspirated plosives even in low-initial tone contexts. We cautiously claim that the observed perceptual pattern is consistent with the robustly represented production pattern, as high-initial tones are more prevalent and salient in the language and exhibit stronger f0 perturbation in the speakers' productions.

Acoustic and aerodynamic variation in voiced plosives

This study investigates variation in the production of word-initial /b, d, ɡ/ by native speakers of English in Mississippi. Forty speakers were recorded reading a short passage and a series of words in isolation. As previously found in this geographic region, phonetic realizations of /b, d, ɡ/ included both short positive and long negative VOTs, with speakers who identified as African American producing plosives with negative VOTs more often than those who identified as Caucasian American; however, negative VOTs were observed among both groups of speakers. Amplitude trajectories and spectral characteristics during the voice bar of the plosives with negative VOTs suggest that phonetic realizations of /b, d, ɡ/ included both prevoiced and prenasalized plosives. As with frequency of negative VOTs, prenasalization was observed among both groups but was higher among African American participants than Caucasian American participants. Nasal airflow data collected from a subset of the participants confirmed that plosives with nasal-like spectral characteristics were produced with greater nasal airflow than those lacking those characteristics. Converging acoustic and aerodynamic evidence indicate that /b, d, ɡ/ variants in Mississippi include unaspirated plosives, prevoiced plosives, and prenasalized plosives. These results also provide evidence of socio-ethnic variation in the production of /b, d, ɡ/.

Plosive voicing acoustics and voice quality in Yerevan Armenian

Yerevan Armenian is a variety of Eastern Armenian with a three-way voicing contrast that includes voiced, voiceless unaspirated, and voiceless aspirated stops, but previous work has not converged on a description of how voice quality is involved in the contrast. We demonstrate how voice quality can be assessed in a two-dimensional acoustic space using a spectral tilt measure in conjunction with a measure of spectral noise. Eight speakers produced a list of words with prevocalic word-initial and postvocalic word-final plosives. The results suggest that Yerevan Armenian has breathy-voiced plosives which are produced with closure voicing and a relatively spread glottis that is maintained into a following vowel. These qualitatively differ from some Indic ones in that they do not have an extended interval of voiced aspiration after the closure. For the voiceless unaspirated plosives, most speakers produced acoustically modal voiceless plosives, although two showed evidence for some glottal constriction and tensing. Many acoustic cues contribute to overall reliable discriminability of the three-way contrast in both initial and final position. Nevertheless, closure voicing intensity and aspiration duration together provide a robust separation of the three categories in both positions. We also find that back vowels are fronted after the breathy-voiced plosives, which supports a historical analysis in which early Armenian voiced stops were also breathy, rather than plain voiced.

Effects of aspiration and vowel context on lip and jaw kinematics in Cantonese bilabial plosive production

The present study examined the possible effects of aspiration and vowel context on lip and jaw movements during production of Cantonese bilabial plosives /p/ and /ph/. VCV syllables were randomly produced by 30 adult native Cantonese speakers. Movement of upper lip, lower lip, and jaw during speech production was recorded using electromagnetic articulography. Kinematic analysis of lip and jaw movements during the opening phase of bilabial plosive production revealed a significant aspiration effect, especially on vertical displacement and velocity of the jaw. Such effects were consistent across all vowel contexts. Similarly, a significant aspiration effect was observed in vertical displacement of the lower lip. These findings suggest that muscular force is the main driving force in the production of unaspirated bilabial plosives.

Emergent tonogenesis in Afrikaans

Afrikaans is usually described as having a contrast between prevoiced and voiceless unaspirated plosives ([b]-[p], [t]-[d]). This study documents an ongoing change in the pre-vocalic realization of the contrast. Preliminary data from five speakers show that all speakers produce some phonologically voiced plosives without prevoicing, with frequency of devoicing ranging from 30% to 85% across speakers. This devoicing is nearly categorical: VOTs of devoiced plosives average 12 ms and those of phonologically voiceless plosives average 17 ms. (By comparison, VOTs of voiced plosives average around Ő130 ms.) The contrast appears to be preserved in the F0 contour of the following vowel, which is 50 to 100 Hz lower (depending on the speaker) after phonologically voiced than after phonologically voiceless plosives. The F0 difference continues through at least 70% of the vowel. However, post-plosive F0 variation is not contingent on devoicing, e.g., F0 contours after phonological /b/ are the same regardless of whether the production is [p] or [b]. In these preliminary data, the magnitude of the F0 difference is linked to speaker age, with younger speakers showing a larger difference. Data from a larger group of speakers are being analyzed and will be presented.

Masked Auditory Feedback Affects Speech Motor Learning of a Plosive Duration Contrast

Adult speakers have developed precise forward models of articulation for their native language and seem to rely less on auditory sensory feedback. However, for learning of the production of new speech sounds, auditory perception provides a corrective signal for motor control. We assessed adult German speakers' speech motor learning capacity in the absence of auditory feedback but with clear somatosensory information. Learners were presented with a nonnative singleton-geminate duration contrast of voiceless, unaspirated bilabial plosives /p/ vs. /pp/ which is present in Italian. We found that the lack of auditory feedback had no immediate effect but that deviating productions emerged during the course of learning. By the end of training, speakers with masked feedback produced strong lengthening of segments and showed more variation on their production than speakers with normal auditory feedback. Our findings indicate that auditory feedback is necessary for the learning of precise coordination of articulation even if somatosensory feedback is salient.

/u/ fronting and /t/ aspiration in Māori and New Zealand English

AbstractThis article examines the relationship between the frontness of /u/ and the aspiration of /t/ in both Māori and New Zealand English (NZE). In both languages, these processes can be observed since the earliest recordings dating from the latter part of the nineteenth century. We report analyses of these developments for three groups of male speakers of Māori spanning the twentieth century. We compare the Māori analyses with analyses of related features of the speakers' English and of the English of monolingual contemporaries. The occurrence of these processes in Māori cannot be seen simply as interference from NZE as the Māori-speaking population became increasingly bilingual. We conclude that it was the arrival of English with its contrast between aspirated and unaspirated plosives, rather than direct borrowing, that was the trigger for the fronting of the hitherto stable back Māori /u/ vowel together with increased aspiration of /t/ before both /i/ and /u/.

An Acoustic Study of Contrasting Plosives and Click Accompaniments in Xhosa

The phonetic manifestation of distinctive plosive types and click accompaniments in Xhosa was investigated with measurements of voice onset time (VOT), closure duration, voicing during closure, and burst amplitude. There is a high degree of interspeaker as well as token-to-token variability in the voiceless unaspirated plosives and clicks concerning their pronunciation with or without audible ejection. The plosives are much more frequently ejective than the corresponding clicks. If present, ejection is manifested by increased VOT, burst amplitude, or both. Duration of voicing during closure is substantial only in the implosive, but not in the ‘voiced’ plosives and clicks. After nasals the percentage of voicing during closure is high in ‘voiced’ plosives due to the very short closure duration found in that context; in the post-nasal ‘voiced’ clicks closure is mostly reduced to zero. Aspirated plosives and clicks in Xhosa show VOT values that are on average relatively long when compared to other languages. Closure duration tends to be shorter in aspirated plosives and clicks than in other categories.

A hierarchical perception-linked model for machine recognition of phonemes

The present paper describes a hierarchical perception-linked model (HPLM) for recognition of all phonemes that have either characteristic formant structures or significant effects on the formant structures of the adjoining phonemes. The model essentially converts the multiclass multiparameter classification problem into a hierarchy of two-class single-parameter classification problems. The model is based on the perceptual phenomenon of substitution of F 1 and F 2 by a composite formant when their distance is less than a certain threshold and of comparison with stored prototypes otherwise. It is further shown that the above two perceptually different situations can also be viewed as the composite frequency lying between F 1 and F 2 in one situation and that lying below F 1 in the other situation. The model is tested on adequate samples from Telugu vowels and laterals, Telugu unaspirated plosives, and Bengali vowels for many speakers. The recognition scores obtained for Telugu vowels, Telugu plosives, and Bengali vowels are 79%, 72%, and 83%, respectively.

Glottal gestures in Hindi plosives

Glottal gestures during bilabial plosives of Hindi were investigated using a photo-electric glottographic technique. Actual and nonsense words of the CV, VCV and VC type were used, where C was one of the plosives /p ph b bh/ and V was the vowel /i/. The vowel following C in CV words and preceding C in VCV and VC words was stressed. The words were embedded in the carrier sentence /didi_bohje/(Elder sister_(please) say). The results show that: the voiced unaspirated plosives are generally produced with a closed glottis and vibration of the vocal folds; the unvoiced unaspirated plosives may be produced either with a closed or an open glottis, but with non-vibrating vocal folds; the voiced aspirated plosives are produced with a closed glottis during part of the closure interval and with an open glottis during part of the closure interval and all of the noise interval, but with vibrating vocal folds throughout; and the unvoiced aspirated plosives are produced with an open and quiescent glottis. The glottis is narrowly open during the unvoiced unaspirated plosives, moderately open during the voiced aspirated plosives and widely open during the unvoiced aspirated plosives. Glottal opening for the unvoiced unaspirated plosives begins somewhat before the articulatory closure and ends immediately after the articulatory release, for the voiced aspirated plosives it begins appreciably before and ends much after the articulatory release, and for the unvoiced aspirated plosives it begins somewhat before the articulatory closure and ends much after the articulatory release. These results are compared with those reported from other languages.

Recognition of unaspirated plosives--A statistical approach

In this paper the results of a study of the computer recognition of unaspirated plosives in commonly used polysyllabic words uttered by three different informants are presented. The onglide transitions of the first two formants and their durations have been found to be an effective set of features for the recognition of unaspirated plosives. The rates of transition of these two formants as a feature set have been found to be significantly inferior to the features mentioned earlier. The maximum likelihood method, under the assumption of a normal distribution for the feature set, provides an adequate tool for classification. The assumption of both intergroup and intragroup independence of the features reduces recognition scores. A prior knowledge of target vowels is found necessary for attaining reasonable efficiency. A prior knowledge of voicing manner improves classification efficiency to some extent. The physiological factors responsible for the variation of the recognition score for the various plosives are discussed. For labials and velars the recognition score is very high, nearly 90 percent. An attempt to correlate the dynamics of tongue-body motion with the variations in recognition scores has been made. Back vowels as targets have been found to give improved classification of the preceding consonants. A comparison of the result of machine recognition with those of published results on perception tests has been included. The results are found to be of the same order.

Effect of fuzzification on the plosive cognition system

Fuzzy algorithms provide a simpler and more powerful approach than statistical decision methods for describing non-ideal (fuzzy) environments in which there exists no precise boundary between the categories due to inherent vagueness rather than randomness. This paper attempts to demonstrate the effectiveness of such an algorithm when applied to the computer recognition of patterns of biological origin such as Telugu unaspirated plosives in initial position of large number of utterances in CVC context. A multieategorizer is described in which the fuzzy processor embodies a fuzzy property extractor and a similarity matrix generator. A provision fur controlling fuzziness in property sets had been made by keeping two parameters. ‘exponential’ and ‘denominational’ fuzzifiers, in the components of property matrices ; their effect on recognition score is also studied. Machines’ performances are explained by plotting curves and through confusion matrices when transition, duration and slope of transition from the ...

Glottal dynamics during Hindi bilabial plosives and the glottal fricative

The dynamics of glottal behavior during the production of bilabial plosives and the glottal fricative was investigated in Hindi, which possesses contrasts between aspirated and unaspirated plosives, both in voiced and unvoiced categories. Minimal pairs of meaningful and nonsense words with /p/, /ph/, /b/, /bh/, and /h/ occurring in prevocalic, intervocalic, and postvocalic positions were embedded in the sentence /didi-bolIye/. Photoelectric glottograms together with audio signal were recorded and examined. The results indicate that (1) the opening gesture of the glottis is a necessary condition for the production of the glottal fricative and unaspirated plosives, both voiced and unvoiced; (2) unaspirated plosives, both voiced and unvoiced, may be produced with or without opening gesture of the glottis; (3) regardless of aspiration, voiced plosives are produced with uninterrupted vocal-fold vibrations, whereas unvoiced plosives are not; (4) glottal fricative is produced without interruption of vocal-fold vibrations; (5) duration and extent of glottal opening do not seem to be systematically related; (6) there is no apparent direct correlation between the degree of glottal opening at the time of oral release and the degree of aspiration; (7) the initiation of opening and closing gestures of the glottis, in relation to oral closure and release, respectively, is variously timed for various plosives.

On Chinese Unaspirated Plosives and Africates

On Chinese Unaspirated Plosives and Africates